Workers fled the office of a Baltimore television station Tuesday morning after a vehicle smashed through the front entrance, and the possibly armed driver was unaccounted for, Baltimore County police said.

Police shut down roads in the Towson community near ABC-affiliate WMAR-TV, ordered the nearby St. Pius X School to enter a lockdown and advised people in the area to use social media with caution.

There were no reports of injuries. The station's reporters said on Twitter that the vehicle was a dump truck or a landscaping truck.

Police said the first call to 911 was made at 11:45 a.m., reporting that a man was banging on the station's door trying to get in. Minutes later, the station called 911 again. This time, the man had brought the truck into a lobby.

A photo from the scene suggested the truck escalated a short staircase, barged through a set of doors and came to rest in a lobby. One reporter said multiple attempts were needed to break through the entrance.

The station reported the man may have barricaded himself in the building, prompting a SWAT team search of the premises that continued Tuesday afternoon.

The E.W. Scripps Co., which owns WMAR-TV, lists the affiliate as the 11th commercial television station to ever be created.

The Archdiocese of Baltimore said everyone at the St. Pius school was safe and that it was praying for a safe resolution at the TV station.